Great need is evident for effective interventions to prevent/reduce at-risk drinking (ARD; combinations of quantity and frequency that place one's health at risk) among underage college undergraduate students. Currently in the United States an average of three college students die each day in alcohol-related car crashes, while thousands more are victims of alcohol-related violence and assault, and risk their health and professional futures through ARD. This study will address the following Aims. 1) Develop a theory-directed four-session, web-based tailored brief motivational intervention to prevent/reduce ARD among underage freshmen college students (i.e., aged 18 through 20 years). Recruitment and random assignment of study participants from the University of Michigan freshmen class to either a Tailored Brief Intervention (TBI) or web survey only (WSO) condition will occur in the first two months of one academic year. Participants in both conditions will be asked the same baseline, tailoring and follow-up questions and will visit the study website the same number of times, but only the TBI group will receive the tailored intervention sessions. TBI messages will be tailored on each TBI group member's demographics, ARD level, and behavior change characteristics, and tailoring information needed to formulate the intervention messages will be measured as needed during the four sessions. Both groups will be followed-up with a brief Web-based survey at six, 12, and 18 months. 2) evaluate the efficacy of the web-based TBI to reduce ARD by comparing the TBI and WSO groups on ARD outcomes at baseline, six, 12, and 18 months post intervention. The final sample size is planned to be 540. Intervention main effects and interactions with sex will be tested. 3) Identify the baseline ARD behaviors and attitudes of participants who: complete 1,2,3, and four intervention/control sessions on the Web; and complete the 6-, 12-, and 18-month follow-ups. The study will examine predictors of participation and dropout. If effective, the proposed intervention could be inexpensively modified to deliver effective interventions to large numbers of university students, members of other populations, and to target other health risk behaviors.